[Ximena]

Hello,

I'm really new in openFoam. I'm trying to simulate wind-flow around a 39-story building , I could run the windAroundBuildigs tutorial and to starting I just tried replacing the buildings.obj.gz file (inside ...buildings/constant/triSurface folder) for mytower.stl.zip and also for mytower.obj.zip.. But it didn't work. I also opened the buildings.obj file and y i noticed that mytower is 100 time bigger than the buildings from the tutorial. Could someone explain to me how can i change the BC to run the same tutorial with mytower model (real-scale)?
I would really appreciate your help.

Ximena

[RobertHB]

Hello ximena,
i guess you have several options here. 1) rescale your tower.stl with e.g. Blender or 2) resize the blockMesh of windAroundBuildings so that your tower.stl fits inside.

Anyhow, you should place your tower.stl inside constant/triSurface not the zipped version. And remember that you have to remesh the case (run blockMesh as well as snappyHexMesh) so that you structure appears in the mesh.

[Ximena]

Thanks for your reply, I tried doing that
- Reduce tower.stl (on Fusion 360) because was faster for me than resize blockMesh .
- Open both of them on Paraview (and Fusion) to check if the origin and sizes matched, and those matched.
-Extra: Edit snappyHexMesh and surfaceFeatureExtract textEdit files (changing buildings.obj to buildings.stl).
-Run
It works thanks a lot!!

Now, could you help me again. I want to reproduce it but to real-scale , i guess that i have to edit blocMeshDict, is this the only file should I edit? and what parameter do I change?

[RobertHB]

Originally Posted by Ximena

Thanks for your reply, I tried doing that
- Reduce tower.stl (on Fusion 360) because was faster for me than resize blockMesh .
- Open both of them on Paraview (and Fusion) to check if the origin and sizes matched, and those matched.
-Extra: Edit snappyHexMesh and surfaceFeatureExtract textEdit files (changing buildings.obj to buildings.stl).
-Run
It works thanks a lot!!

Now, could you help me again. I want to reproduce it but to real-scale , i guess that i have to edit blocMeshDict, is this the only file should I edit? and what parameter do I change?

Option 1: Change your blockMesh dictionary and your .stl to reflect the scale you want. Most likely the easiest way.

Option 2: Make use of the dynamic similarity of the flow. That would mean keeping the Reynolds number constant between your actual and mesh size, while changing the viscosity. Here is a link to a paper by Bolster et al. (2011), which is a pretty good and understandable introdutction to the topic.